By Matt McMillen
WebMD Health News
Reviewed by Brunilda Nazario, MD
Nov. 9, 2015 -- Although cortisol is known as the "stress hormone," researchers suspect it plays a much larger role in our health.
A recent study, for example, linked cortisol to memory in older adults. People with unusually high nighttime cortisol levels had reduced brain size and did more poorly on cognitive tests. Scientists are also investigating the hormone's ties to heart disease risk and weight, to name a few.
"The effects of cortisol are felt over virtually the entire body," says endocrinologist Robert Courgi, MD, who practices at Southside Hospital in Bay Shore, N.Y.
But researchers are just starting to understand what those effects are.
"Many of us endocrinologists are interested in this idea that our day-to-day cortisol levels, whether they are high or low, might make a difference to our overall health," says Lynnette Nieman, MD, chief of the Endocrinology Consultation Service at the National Institutes of Health Clinical Center. "But there aren't a lot of data that speak to that question."
In the brain study, researchers tested morning and evening cortisol levels in the saliva of 4,244 older adults. Those with higher evening levels appeared to have smaller brain volume and worse brain function, like processing speed and "executive functioning" skills, which include paying attention, switching focus, planning, and organization. Those with higher morning cortisol levels, though, appeared to have better brain function.
But the researchers couldn't say which came first: unusually high cortisol or the reduced brain size.
"Clearly there is a physiologic relationship," says Courgi, who wasn't involved in the research. "But is it cause and effect? Is it because there's too much cortisol that you're having memory problems? Or does the loss of memory lead to elevated cortisol?"
Another link researchers are looking into is the hormone's potential role in the number you see when you step on the scale.
"There's concern that cortisol causes weight gain, but there's also the question of cause and effect," Courgi says. "Is it the weight gain that elevates the cortisol, or the elevated cortisol that leads to weight gain?"
It's made in the adrenal glands, which are located just above the kidneys. That production is controlled by hormones released by the hypothalamus and the pituitary gland, both of which are found in the brain.
In times of great stress, cortisol floods the bloodstream, allowing energy sources to be available and preparing the body for the stress. When working properly, brain signals tamp down the production of cortisol after the danger has passed.
"It's an important regulating feature that keeps us from getting really high cortisol levels," Nieman says.
That feature doesn't get your cortisol levels completely back to normal though, she says. While that may be cause for concern, especially for people who remain under constant stress, it's a question that needs more research, Nieman says.
Stress can be psychological, such as that caused by problems at home or at work. It can also be physical. Fevers and low blood sugar, for example, are both stressors, Courgi says.
Stress isn't the only cause of higher cortisol levels. Other culprits include:
- Lifestyle habits, such as heavy drinking, smoking, lack of sleep, and a bad diet
- Benign tumors on the pituitary gland or, more rarely, on the adrenal glands, can cause cortisol production to skyrocket, a condition called Cushing's syndrome.
"There's not a lot of evidence to suggest that people under chronic stress all have chronically elevated cortisol," Nieman says. "But if they do, do they have high risk of medical diseases? And, if so, is it the high cortisol that's causing it? You'd need to do a study that shows that reducing cortisol also reduced the risk of disease."
Benefits of Lowering Cortisol?
Courgi and Nieman say more research is needed before they can say for sure that lowering levels of the hormone leads to better health. Still, Courgi says the evidence on cortisol's effect on memory is compelling.
"The knowledge we have now certainly suggests that if you can reduce stress, reduce cortisol, you can prevent memory loss," he says, "but we need more research to prove it."
Practice healthy habits if you want to lower cortisol, he says. Quit smoking, and ease up on alcohol. Also, "mindful meditation, which calms and relaxes you and stops the wheels from spinning, has been proved to lower cortisol levels."
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